The waste water effluent from many industrial facilities, such as steel plants and fertilizer manufacturing plants, contains excessive amounts of ammonia, derived in some cases from the hydrolysis of urea. The ammonia concentration must be reduced to acceptable levels before the waste water is discharged into the aquatic environment, since ammonia exerts a considerable oxygen demand on the receiving water, it is toxic to some forms of aquatic life, and plays a role in eutrophication of water bodies.